Lift gates for lifting objects into and out of vehicles are relatively well known. Typically, these lift gates are hydraulically operated and are mounted at the rear of a large vehicle such as a tractor-trailer. The lift gates allow objects to be easily loaded into the vehicle and unloaded from the vehicle by raising and lowering the objects.
Some side-door lifting apparatuses have been contemplated in the prior art. For example, U.S. Pat. No. 4,479,753 to Thorley discloses a retrofittable wheelchair lift for passenger vehicles. The lift assembly is hinged on a vertical axis to a door post adjacent the door hinge. When the door opens, the lift assembly pivots away from the door opening. A horizontal carrier slides further outwardly so that the lift assembly clears the side of the vehicle. A single telescoping vertical carrier is deployed by a hydraulic actuator to lower a platform which then rotates away from the vertical carrier along a horizontal hinge located at the lower edge of the vertical carrier. This lifting apparatus requires a horizontal carrier to ensure clearance of the platform from the side of the vehicle. Also, this lifting apparatus is mounted onto the door of the vehicle which restricts both the weight of lifting apparatus and the amount of weight that can be lifted.
U.S. Pat. No. 4,456,421 to Robson discloses a lifting apparatus carried in an inoperative compact form within the interior of a vehicle and deployed in an operative position outside the vehicle. A pillar is provided in the interior of the vehicle near either a side or rear door. The disclosed lifting apparatus utilizes a parallelogram linkage to raise and lower the platform. This lifting apparatus is directed to the lifting of wheelchairs. Again, this design restricts the amount of weight that can be lifted.
The present invention contemplates a new and improved lift gate construction which is simple in design, effective in use, and overcomes the foregoing difficulties and others while providing better and more advantageous overall results.
According to one aspect of the invention a lift gate is provided which is associated along the side of a vehicle. For instance, the lift gate may be located anywhere along the side of a tractor-trailer.
According to another aspect of the current invention, the lift gate folds so as to be recessable within the side of the vehicle.
According to another aspect of the current invention, the side lift gate has a platform operatively connected to a telescopic column. The column allows the platform to be raised and lowered so that objects may be loaded into and out of the side of the vehicle.
According to another aspect of the invention, a lifting apparatus adapted for use in an associated vehicle having a floor and one upright wall having an opening therein is provided. The lifting apparatus is operable between a stowed mode and a deployed mode. The lifting apparatus comprises a platform having a generally planar loading surface and adapted for movement between a folded position and an open position, elevator means for selectively moving the platform between an upper level and a lower level, first pivot means being operable to pivot the elevator means and the platform while the platform is in the folded position from an interior side of the opening to an exterior side of the opening about a first pivot member having a first axis generally normal to the floor, and second pivot means for selectively pivoting the platform between the folded position and the open position about a second pivot member having a second axis perpendicular to the first axis.
According to another aspect of the invention, the lifting apparatus further includes means for controlling the pivotal motion of the platform about the second axis.
According to another aspect of the invention, the first pivot member comprises a post adapted for mounting to the floor of the vehicle at a position displaced from the opening.
According to another aspect of the invention, the elevator means includes a telescoping member operable along an axis parallel to the first axis wherein a lower portion is adapted to telescope within an upper portion, the telescoping member being spaced from the first pivot member.
According to another aspect of the invention, the lifting apparatus further includes a first cross member extending between the first pivot member and the first portion of the telescoping member.
According to another aspect of the invention, the lifting apparatus further includes first switching means for activating the elevator means wherein the first switching means is located on the elevator means.
According to another aspect of the invention, the lifting apparatus further includes second switching means for activating the elevator means wherein the second switching means is selectively moveable with the platform.
According to another aspect of the invention, each of the up and down movements of the platform is accomplished through hydraulic means.
According to another aspect of the invention, a method for utilizing a lift gate apparatus is provided. The method includes the step of pivoting the elevator means and platform while the platform is in a folded position from the interior side of the opening to the exterior side of the opening about the first pivot member; pivoting the platform from the folded position to the open position about the second pivot member; and, utilizing the elevator means to lower the platform to the lower level.
One advantage of the present invention is that semi-tractor trailers can be retrofitted with the lifting apparatus to provide access to the cargo area via a side door.
Another advantage of the present invention is that the lifting apparatus can be carried within the vehicle interior to prevent unnecessary exposure to the elements and corrosive road salt.
Still other benefits and advantages of the invention will become apparent to those skilled in the art upon a reading and understanding of the following detailed specification.